Various types of acoustic devices have been used over the years. One type of acoustic device is a receiver having a deflecting armature. Such a receiver typically includes a coil, diaphragm, bobbin, stack, among other components contained within a receiver housing. Other types of acoustic devices may include other types of components. A motor of the receiver typically includes the coil, a yoke, such as a stack, and the armature, which together form a magnetic circuit.
In operation, an electrical signal creates a changing magnetic field that moves the armature relative to permanent magnets. The armature moves a drive rod, which moves a diaphragm to produce sound presented to a listener. The yoke provides a support structure for the magnets and in some cases provides portions of the magnetic flux path created when the receiver is operated.
Receivers are use in various electronic devices such as cellular phones, hearing aids, personal computers, and tablets. As the years have progressed, it has become desirable to make these electronic devices smaller. One limitation in making the electronic devices smaller is that when receivers are included, the size of the yoke often necessitates a larger device. The problems of previous approaches have resulted in some user dissatisfaction with these previous approaches as further miniaturization has become difficult to achieve.
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